Without even watching the news, Eric Gustafson knew something dramatic had happened in the ocean.

“The phones stopped ringing, like literally stopped for the first time ever,” Gustafson said about the weeks following July 30, the day a great white shark attacked Denver businessman Christopher Myers at Ballston Beach in Truro.

Gustafson, owner of Fun Seekers, the oldest surf school on Cape Cod, has been in business for 21 years in Wellfleet.

“When the phones did ring, it was somebody calling to cancel their lesson,” he said.

One shark attack in 76 years does not make a trend, but scientists say it’s inevitable there will be a second or third great white attack — possibly a fatality — as the local seal population explodes in areas near popular Cape beaches. And that has business owners worried.

“God forbid, if there was another. We’d see a reversal to last summer, but more intense,” said Josh Smith, manager at Sickday Surf & Skate, a Wellfleet shop. The store’s surf lessons dropped off the cliff after Myers was attacked last summer, Smith said.

Some people, however, who have studied or seen the repercussions of shark attacks in other communities, say the public’s ability to put such events in context is underestimated and the economic fallout rarely extends beyond a few weeks.

There’s no question a lot of money is at stake.

Barnstable County ranks fourth of 14 counties in the state for tourism expenditures with nearly $852 billion spent by visitors in 2011. Of that, more than $217 million went to payrolls.

Tourism — especially beach tourism — also means money for towns. Orleans beach parking revenue is more than $900,000 a year, and Wellfleet approaches that number, as well. Even a small town like Truro takes in more than $300,000. A portion of this money usually goes into the towns’ general fund to support other town departments and expenses. Another portion pays for beach maintenance and staffing.

Even the federal government benefits from the popularity of the beach. In 2011, the Cape Cod National Seashore, with its nearly 2,400 beach spaces, took in more than $1.4 million in parking fees.

A series of shark attacks, even if they occurred on the Outer Cape, would affect tourism across the entire region, Cape Cod Chamber of Commerce CEO Wendy Northcross believes. The beach consistently is cited as the number one reason tourists come to Cape Cod in chamber surveys, Northcross said.

After the attack on Myers last summer, her office fielded scores of concerned calls, she said. Many tourists coming here for a summer vacation do not distinguish between the regions or towns, she said.

“It’s Cape Cod that gets the reputation, not Chatham or Barnstable, or Falmouth,” Northcross said.

But some experts claim there’s no data showing that shark attacks are bad for business over the long run.

“There is a really big difference between the way politicians think the public will react and the way they really do,” said Christopher Neff, a third-year doctoral student at the University of Sydney in Australia who has studied the economic implications of shark attacks.

“Fearing there will be a drop in tourism is not evidence there will be,” he said. “If there was a lot of data about businesses going out of business, I would have seen it.”

Surviving an attack

At least one California town has survived a fatal shark attack economically.

Avila Beach is a true beach town of fewer than 2,000 on California’s Central Coast that advertises itself as a quiet destination for families and retirees. Following a massive spill from a nearby oil pipeline in the 1990s, the entire town was rebuilt and has that Disney feel of clean, colorful architecture. The half-mile crescent of beach is sheltered by headlands from winter winds and Avila can be summery any time of year. Tourism is the number one draw.

On Aug. 20, 2003, a great white shark — a rare sight at the Avila beach — likely was investigating a group of sea lions when it attacked Deborah Franzman, 50, while she was doing her daily swim within a few hundred feet of shore. Franzman bled to death from a massive thigh wound before she could be rescued by lifeguards.

Shark warning signs went up, closing the beach to swimming for days, Crystal Graham, 25, who works at The Sea Barn, a waterfront gift shop, recalled. But Graham said residents believed it was an isolated incident, a case of mistaken identity that occurred because Franzman was wearing a black wetsuit, had flippers on and was swimming close to sea lions.

It didn’t affect the businesses for long, according to local business owners and residents interviewed by the Times on a trip last winter. On a warm January afternoon, the beach and the strip of beachfront bars and restaurants were filled with college students, families and couples.

“This is crammed (on summer days),” said Joe Stanton who was walking the beach with his wife, Sue. “I haven’t seen a white shark,” he said.

‘The public gets it’

Neff conducted a study in two beach towns near Cape Town, South Africa, where there have been six fatalities in the past six years. It showed little change in the public’s attitude toward great whites and public safety organizations before and after a horrific attack on a swimmer at Fish Hoek beach on Sept. 28, 2011, that took portions of both his legs.

Although the sample size was small, Neff concluded that people’s attitudes about great white sharks were more nuanced than he’d expected, in that they didn’t assess blame for the attack on the sharks, or on the shark detection service, known as Shark Spotters, tasked with seeing great whites and alerting beachgoers and public safety personnel to their presence.

In the case of the Fish Hoek attack, the public was given the facts and analysis within 48 hours, Neff said. Shark Spotters watchmen had seen the shark swimming close to the beach and the beaches had been closed. Michael Cohen, the victim, ignored warnings by lifesavers as well as the flags that announced the closure.

“The public gets it when they are told there are sharks and to use common sense,” Neff said.

The attack on Cohen was filmed and drew more than a million Internet viewers. Another survey of more than 400 people taken a month after the attack by the local surf lifesaving club and a community organization found that 17 percent of respondents had canceled their planned vacation at Fish Hoek beach following the attack.

Seventy-seven percent said they would continue to use the beach, but only 61 percent said they would go in the water.

Chatham Chamber of Commerce Executive Director Lisa Franz agreed that education is important in keeping the public calm — and attracting tourists.

The chamber and its affiliated merchants association recently leased a building to begin a shark education center that would take advantage of research being done by scientists like state shark researcher Greg Skomal and scientists on board OCEARCH, a privately owned and financed vessel that will be tagging great whites off Chatham this August. The emphasis will be on incorporating this research into the curriculum in local schools.

“We just have to be educated about our own environment,” Franz said. “The town could be like a national park in a way. The sharks are a natural resource. They are here; why not study them?”

Seals out, sharks in

The economic impact can also be beneficial to local businesses, some say.

“As soon as that first (great white shark) sighting hits the news, my phone rings off the hook. They want to see them,” said Keith Lincoln of The Monomoy Island Ferry, which offers seal cruises on two different vessels.

After the first seals established a colony of around 100 adults in 1990, Lincoln built three boats to ferry people out to Monomoy. He now makes four trips a day, and the prospect of seeing a shark, although rare, is enough to entice people.

“Interest in sharks is always big,” Lincoln said. “Walk through the stores downtown, everything is great white. It used to be seal merchandise.”

“Wildlife will always be a draw,” he added.

Lincoln can ferry up to 20 passengers, and he charges $35 for adults and $30 for children. There are at least four companies, including Lincoln’s, that offer seal cruises to Monomoy. At one point, when there were five local boats making trips to Monomoy, Lincoln estimated the combined vessels transported 10,000 people on seal tours annually and they spent an estimated $50 a head in local stores, on lodging, or other goods before and after their trip.

Business also is pretty good for Fun Seekers so far this year, said surfing instructor Robert Denninger, 21.

At 8 a.m. on a foggy Friday at Marconi Beach, he had a group lesson for four, followed by a private lesson at 9:30 a.m. A little up the beach, two more Fun Seekers instructors led sand drills for 12 would-be surfers on how to stand up on a board, then marched them down the beach and into the water.

Carly Long, 20, originally from Maryland and now living in Kentucky, hadn’t heard about the Cape’s great whites but felt she had more to worry about than sharks.

“I can’t swim,” she confessed. Denninger held the tail of her board while standing in waist-deep water and gently pushed her into a wave. As she sped toward shore, Long struggled to her knees, got one foot up and threw both hands up in mock triumph before rolling into water.

“I’m not worried about it,” she said of the sharks.

Alun Walpole, 24, who lives in Washington, D.C., had more luck standing up on his board. He was definitely smitten with the surf bug and when asked about the sharks, he replied with the aplomb of a hardened surfer.